Coffee has a reputation for increasing your urge to poop. This could be because it changes how your gut behaves.
Coffee triggers the release of digestive juices and hormones in your stomach and small intestine. It also stimulates contractions in your large intestine.
So, as research indicates, drinking coffee can encourage the movement of food through the gut for some people. It doesn’t have this effect on everyone.
Our survey showed that constipation is a common issue. We also know that gut health could play a role in healthy bowel movements.
The ZOE at-home test analyzes the health of your gut microbiome and how your levels of blood fat and blood sugar respond to different foods. With this information, our personalized nutrition program can show you the best foods for your gut and overall health.
Find out how it works by taking our free quiz.
Coffee and the gut
Coffee affects your gut in different ways.
In your stomach, it triggers the production of gastrin, a digestive hormone that stimulates the release of stomach acid.
Coffee also stimulates the release of another digestive hormone, called cholecystokinin, or CCK.
It triggers the release of enzymes from the pancreas that break down food, as well as bile from the gallbladder. These enter your small intestine.
In your large intestine, coffee increases activity by stimulating gut muscle contractions. So, basically, coffee “gets things moving.”
Meanwhile, there’s another gut-related force called the gastrocolic reflex. This is a wave of movement that propels food through the gut to make room for new food.
It’s triggered by eating when the stomach is stretched. Since many of us have three meals a day, the gastrocolic reflex typically happens three times a day.
Both gastrin and CCK could play a role in the gastrocolic reflex. So, this might be another way that coffee encourages bowel movements for some people.
What effect does caffeine have?
Coffee is a popular source of caffeine. This naturally occurring compound exists in more than 60 plant species.
A cup of caffeinated coffee contains around 95 milligrams of caffeine. And cup of decaf contains around 2 mg, a very small amount.
Caffeine is known for its ability to “wake up” your gut.
In research cited in a recent review, caffeinated coffee triggered as much activity in the large intestine as a 1,000-kilocalorie meal.
The effect was also 60% stronger than water and 23% stronger than decaf coffee.
Does decaf coffee have the same effect?
Decaf might not affect your gut in the same way as caffeinated coffee, but it could still increase your urge to poop.
Caffeine stimulates activity in the digestive system that could make some people need to poop.
Decaf coffee has less of an impact, but it could still increase the urge. Studies suggest that this could be due to other compounds in the drink, such as polyphenols.
Does the timing of your coffee matter?
When you have your coffee can affect its impact on your gut.
The gastrocolic reflex is more active in the morning and after meals. So, you might notice more of an urge to poop after your morning coffee, compared with your afternoon coffee.
Your body clock likely plays a role, too. The gut functions differently when you’re eating regularly, compared with when you’re asleep.
As you might expect, there’s more activity when you’re up and about, including increased gut muscle movement, digestive juices, and nutrient absorption.
What effect does dairy have?
Coffee is a versatile drink. Many of us enjoy it with milk or cream, and these extras can increase gut activity, too.
For some people, very milky coffee can trigger gut symptoms, and the culprit is often a sugar in dairy called lactose.
If your body doesn’t break down lactose, this draws in water as it passes through your gut. It can lead to bloating, gas, and diarrhea.
The issue is called lactose intolerance, and it affects 57–65% of people worldwide.
Adding something with a lot of fat to your coffee, like heavy cream, can trigger the release of extra digestive juices from the pancreas and gallbladder. The result is more water in the small intestine, which can lead to diarrhea.
In fact, 15% of people who took part in The Big Poo Review reported diarrhea.
Whether you get symptoms from adding dairy to your coffee depends on your tolerance levels. Still, adding just a splash of milk or cream doesn’t cause issues for most people, including those with lactose intolerance.
If you’d like to dig deeper, here’s our article on coffee’s health profile.
Join our mailing list
Sign up for fresh insights into our scientific discoveries and the latest nutrition updates. No spam, just science.
Sensitivity to coffee
When it comes to bowel movements, some people are more sensitive to coffee’s effects than others. You might not notice any of these effects.
Also, everyone has a different level of sensitivity to caffeine. It can cause unwanted symptoms, like headaches, restlessness, and disrupted sleep. Decaf has much less caffeine, but it still has some.
Your sensitivity can also change over time. If you drink coffee regularly, you might find that you can tolerate more without any symptoms.
Up to 400 mg of caffeine a day appears to be safe for most people. That’s about 4–5 cups of caffeinated coffee.
If you’re pregnant, you should have no more than 200 mg a day.
Can you stop its effects?
On an empty stomach, you absorb 99% of caffeine within 45 minutes. It peaks in your bloodstream after 1–2 hours.
But if you have coffee with a meal containing fiber, protein, and healthy fats, your gut will absorb the caffeine more slowly.
If you’re looking for this kind of breakfast, smashed avocado on whole grain toast or a bowl of oatmeal with nut butter are two options. But if you’re prone to diarrhea, be careful not to eat too much fiber or fat.
Meals that combine fiber, protein, and healthy fats are also great for moderating your blood sugar and blood fat levels.
ZOE’s personalized nutrition program can help you combine foods in a way that supports your overall health, as well as the “good” bacteria in your gut.
Learn more about what this involves by taking our free quiz.
Can coffee help with constipation?
Since coffee increases activity in the large intestine, it’s become a well-known natural home remedy for constipation.
So, you might be able to use coffee to your advantage if you’re struggling to poop. This is true for regular and decaf coffee.
The best time to give it a go is in the morning and after a meal, when the gastrocolic reflex is at its most active. Having a cup of coffee with your breakfast or just afterward might do the trick nicely.
Coffee could increase your urge to poop by triggering the release of digestive juices and hormones. It may also stimulate the movement of your gut muscles.
It’s not just caffeine that increases your urge to poop. Other compounds in coffee, such as polyphenols, may also increase your gut activity.
Adding a splash of milk or cream is unlikely to cause gut issues, even for people with lactose intolerance.
Still, everyone has different sensitivity to coffee and caffeine. If you’re particularly sensitive to caffeine, decaf may be a better option.
If you struggle to poop, adding a coffee at breakfast time may help.
All about decaffeinated coffee. (n.d.). https://www.ncausa.org/Decaffeinated-Coffee
Caffeine as a factor influencing the functioning of the human body — friend or foe? Nutrients. (2021). https://www.mdpi.com/2072-6643/13/9/3088
Circadian rhythms: A regulator of gastrointestinal health and dysfunction. Expert Review of Gastroenterology and Hepatology. (2019). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6533073/
Coffee consumption. (2023). https://britishcoffeeassociation.org/coffee-consumption/
Effects of coffee on the gastro-intestinal tract: A narrative review and literature update. Nutrients. (2022). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8778943/
Fat emulsion intragastric stability and droplet size modulate gastrointestinal responses and subsequent food intake in young adults. Journal of Nutrition. (2015). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4442113/
Foods to avoid in pregnancy. (2023). https://www.nhs.uk/pregnancy/keeping-well/foods-to-avoid/
Gut microbiota and chronic constipation: A review and update. Frontiers in Medicine. (2019). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6379309/
Lactose intolerance: An update on its pathogenesis, diagnosis, and treatment. Nutrition Research. (2021). https://www.sciencedirect.com/science/article/abs/pii/S0271531721000129
Long-term coffee consumption is associated with fecal microbial composition in humans. Nutrients. (2020). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7282261/
Mechanistic study of coffee effects on gut microbiota and motility in rats. Nutrients (2022). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9699609/
Physiology, gastrocolic reflex. StatPearls. (2023). https://www.ncbi.nlm.nih.gov/books/NBK549888/
Spilling the beans: How much caffeine is too much? (2018). https://www.fda.gov/consumers/consumer-updates/spilling-beans-how-much-caffeine-too-much
Time to recover from daily caffeine intake. Frontiers. (2021). https://www.frontiersin.org/articles/10.3389/fnut.2021.787225/full